The present invention is drawn to compositions and methods for separating desired heterocyclic aromatic amine bases, nucleosides, nucleotides, or sequences of DNA using separation techniques, preferably non-chromatographic separation techniques.
Deoxyribonucleic Acid (DNA) is generally comprised of four different types of nucleotides. These nucleotides are comprised of three components: (1) heterocyclic aromatic amine base; (2) 2-deoxy-D-ribose; and (3) phosphoric acid. The bases are generally from two N-heterocyclic categories, namely pyrimidine and purine, the general structures of which are shown below; respectively. 
In DNA, the two pyrimidine-type bases are cytosine (C) and thymine (T). Additionally with respect to DNA, the two purine-type bases are adenine (A) and guanine (G).
Likewise, Ribonucleic Acid (RNA) is similar to DNA in that they too are comprised of long, unbranched chains of nucleotides joined by phosphodiester bonds between the 3xe2x80x2-hydroxyl of one pentose and the 5xe2x80x2-hydroxyl of an adjacent pentose. However, there are three main differences between DNA and RNA including: (1) the pentose unit in the RNA is D-ribose rather than 2-deoxy-D-ribose; (2) the pyrimidine base found in RNA is uracil (U) rather than thymine (T); and (3) RNA is single stranded rather than double stranded. The three pyrimidine-type heterocyclic aromatic amine bases found in DNA and RNA are shown below: 
The two purine-type heterocyclic aromatic amine bases found in both DNA and RNA are shown below. 
In the case of DNA, a nucleoside is a glycoside in which nitrogen 9 of a purine or nitrogen I of a pyrimidine base is bonded to 2-deoxy-D-ribose. An example is shown below. 
Further, with respect to DNA, a nucleotide is a nucleoside monophosphate ester in which a molecule of phosphoric acid is esterified with a free hydroxy group of 2-deoxy-D-ribose. An example is shown below. 
In the prior art, the separation of nucleotides has primarily been accomplished by utilizing separation devices that selectively bind to the phosphoric acid portion, or the 2-deoxy-D-ribose portion of the DNA. For example, ligand complexes containing zinc, copper, and nickel have been used to selectively bind the phosphoric acid portion of a nucleotide. Though the selectivity of such compounds has been somewhat effective in separating nucleotides from other impurities, these systems and methods do not exhibit high selectivity properties when the desire is to separate one nucleotide from another, e.g., A from T. With these systems, if the desired heterocyclic amine is merely in the form of a nucleoside, there is no phosphoric acid portion present and the separation cannot occur. Additionally, with such compositions, lone heterocyclic aromatic amine bases cannot be separated without being present as an intact nucleotide.
The compositions and methods of the present invention comprise one or more palladium bound ligands that are covalently bonded to inorganic or organic solid supports. These palladium bound ligands bonded to solid supports can be used to separate single heterocyclic amine bases, nucleosides, nucleotides, or nucleotide chains containing specific sequences from other non-desired molecular units present. In one aspect of the invention, each ligand present as part of the composition is individually complexed to a single Pd(II) ion. If there are from 2 to 4 ligands present on a single composition, then each ligand present can be bound to a palladium ion and each ligand should be separated from the other ligands by at least 3 atoms, preferably from 3 to 20 carbon atoms or an equivalent spacer chain.